Downloaded from www.Manualslib.com manuals search engine ANTIPOLLUTION
Exhaust gas recirculation
14
14-2
Exhaust gas recirculation
CIRCUIT DIAGRAM
1Engine
2Injection computer
3Inlet manifold
4Exhaust manifold
5EGR solenoid valve
6Water temperature sensor
REMOVING THE VALVE
The EGR valve is an interference fit in the intake manifold.
To facilitate its replacement it is preferable to remove the manifolds.
PURPOSE OF THE EGR SYSTEM
The recirculation of the exhaust gases is used to reduce the nitrogen oxide
(NOx) content of the exhaust gases.
The passage of gas is authorised by the control of an electromagnetic valve by
the injection computer.
Downloaded from www.Manualslib.com manuals search engine ANTIPOLLUTION
Exhaust gas recirculation
14
14-3
OPERATING PRINCIPLE
The valve is controlled by an RCO signal issued by the
injection computer. The RCO signal permits
modulation of the opening of the valve, and
consequently, the quantity of exhaust gas directed
back towards the inlet manifold.
The computer continuously carries out a test to detect
the position of the EGR valve flap.
OPERATING CONDITIONS
The parameters which determine the actuation of the
EGR valve are as follows:
– the coolant temperature,
– the air temperature,
– the air pressure,
– the accelerator pedal position,
– the engine speed.
The EGR function is cut if:
– the battery voltage is less than 9 volts,
– the engine speed is greater than 3000 rpm.,
– a characteristics map (engine speed/load) exceeds a
given threshold,
– the vehicle speed is less than 12 km/h, the engine
speed is less than 1000 rpm and if the coolant
temperature is greater than 60 ˚C for 40 seconds.
The EGR valve is not supplied after engine start
according to a coolant temperature characteristics
map.
time (s)The electric EGR valve is supplied for 40 seconds on
each return to idling speed if the air temperature is
greater than 15 ˚C.
Coolant
temperature (˚C)
15761R
1
2
4
5
6Solenoid supply
Sensor supply
Sensor earth
Solenoid earth
Sensor output
-20 0 17 20
